Opioid use disorders are a significant public health problem, yet historically, less than 25% of opioid dependent individuals receive opioid agonist therapy (OAT), the most effective intervention for opioid dependence with a broad evidence base. Buprenorphine, approved by the FDA in 2002, provided clinicians with an additional treatment option for OAT, an option available in settings other than methadone dispensing opioid treatment programs (OTP). Yet we are aware of no studies that estimated the extent to which Buprenorphine truly expanded utilization of OAT, or the factors, such as Medicaid policies, associated with greater use. This study will carefully examine the relative access to BUP maintenance treatment in multiple settings vis--vis access to methadone in OTPs in order to develop a better understanding of facilitators and barriers to utilization of BUP specifically ad OAT more generally. Our innovative approach makes use of several rich complementary data sources that contain detailed information about OAT, including the National Survey of Substance Abuse Treatment Services (N-SSATS), the Medicaid Analytic eXtract (MAX) files, and the Treatment Episode Data Set TEDS. We consider the role of community environmental factors and state policies, how they might interact with individual and clinical factors to influene Buprenorphine access and utilization, and in what treatment settings such use occurs. Moreover, by considering office-based opioid agonist treatment as well as substance abuse treatment setting OAT, we can provide insights into factors that actually increase the total number of individuals receiving OAT, from factors that simply cause people to shift forms of treatment. Our findings will provide decision makers with critical information regarding state level regulations and community-level facilitators and barriers associated with increased utilization of OAT generally and Buprenorphine in particular.